Backlight Simulation at Reduced Resolutions to Determine Spatial Modulation of Light for High Dynamic Range Images

• US 20110193896A1
• Filed: 10/02/2009
• Published: 08/11/2011
• Est. Priority Date: 10/14/2008
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Johnson, Lewis
• Granted Patent: US 8,890,902 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 5/009 Global, i.e. based on properties of the image as a whole applied in cameras using an electronic image sensor H04N23/80, H04N23/70
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2340/0407 Resolution change, inclusive of the use of different resolutions for different screen areas
• CPC Class Codes: G09G 3/002 to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: H04N 5/142 Edging; Contouring

Abstract

Embodiments of the invention relate generally to generating images with an enhanced range of brightness levels, and more particularly, to facilitating high dynamic range imaging by adjusting pixel data and/or using predicted values of luminance, for example, at different resolutions. In at least one embodiment, a method generates an image with an enhanced range of brightness levels. The method can include accessing a model of backlight that includes data representing values of luminance for a number of first samples. The method also can include inverting the values of luminance, as well as upsampling inverted values of luminance to determine upsampled values of luminance. Further, the method can include scaling pixel data for a number of second samples by the upsampled values of luminance to control a modulator to generate an image.

Claims

1. A method of generating an image, the method comprising:

inverting values of a pixel characteristic to establish inverted values of the pixel characteristic for a number of first samples;

upsampling the inverted values of the pixel characteristic to determine upsampled values of the pixel characteristic; and

scaling pixel data for a number of second samples by the upsampled values of the pixel characteristic to control a modulator to generate an image,

wherein the number of first samples is fewer than the number of second samples.

2. The method of claim 1 wherein inverting the values of the pixel characteristic comprises:

inverting predicted values of the pixel characteristic,

wherein the predicted values of the pixel characteristic are associated with a model of backlight.

3. The method of claim 1, wherein the pixel characteristic comprises luminance.

4. The method of claim 1, further comprising:

scaling a value of the pixel characteristic as a function of the distance from a light source associated with the backlight to a reference point at which a light source is absent;

wherein;

upsampling the inverted values of the pixel characteristic further comprises interpolating the inverted values of the pixel characteristic for the number of first samples to form the upsampled values of the pixel characteristic for the second number of samples; and

scaling the value of the pixel characteristic comprises one of increasing the value of the pixel characteristic with respect to a peak value of the pixel characteristic and dividing the value of the pixel characteristic by a profiled value of the pixel characteristic.

5. The method of claim 1 wherein inverting the values of the pixel characteristic comprises one of:

inverting each of the values of the pixel characteristic that is associated with a group of pixels to establish an inverted value of the pixel characteristic;

performing a non-linear divide operation to yield a finite value for the inverted value of the pixel characteristic; and

determining whether a value of the pixel characteristic is associated with a range for the values of the pixel characteristic, dividing 1 by the value of the pixel characteristic if the value of the pixel characteristic is associated the first range to establish the inverted value of the pixel characteristic, and assigning a finite value for the inverted value of the pixel characteristic if the value of the pixel characteristic is associated a second range.

6. The method of claim 1 wherein inverting the values of the pixel characteristic comprises:

performing a number of non-linear divide operations to yield finite values for the inverted values of the pixel characteristic,

wherein the number of non-linear divide operations is substantially equivalent to the number of first samples.

7. The method of claim 1 further comprises:

adjusting the inverted values of the pixel characteristic to modify an amount of light transmitted via the modulator, comprising determining a scaling factor based on an operational characteristic of a light source configured to project light onto the modulator, and scaling the inverted values of the pixel characteristic by the scaling factor.

8. The method of claim 1 wherein accessing the model of backlight comprises:

detecting drive levels configured to modulate light sources to form detected drive levels; and

predicting the values of the pixel characteristic based on the detected drive levels for the first samples to establish predicted values as the values of the pixel characteristic to generate the model of the backlight,

wherein a number of the light sources is less than the number of first samples.

9. The method of claim 8 wherein predicting the values of the pixel characteristic comprises:

filtering magnitudes of the detected drive levels to form the predicted values of the pixel characteristic for groups of pixels associated with the light sources by applying a point spread function to the magnitudes of the detected drive levels to form the predicted values of the pixel characteristic.

10. An apparatus comprising:

a repository comprising;

a data structure configured to arrange data representing predicted values of luminance for a number of samples that is greater in quantity than a number of light sources;

a memory comprising;

an inverter module, an upsampler module, and a pixel scaler module; and

a processor configure to;

access the data structure to fetch the data representing the predicted values of luminance,

invert the predicted values of luminance, responsive to executable instructions in the inverter module, to establish a quantity of inverted values of luminance that is substantially equivalent to the number of samples,

upsample the inverted values of luminance, responsive to executable instructions in the upsampler module, to generate a quantity of upsampled values of luminance that is substantially equivalent to a number of pixels, and

scale pixel data by the upsampled values of luminance, responsive to executable instructions in the pixel scaler module, to form a modulation signal to control a front modulator to generate an image.

11. The apparatus of claim 10 further comprising:

an edge luminance enhancement module, the processor being further configured to generate an edge-enhanced value for one of the inverted values of luminance, responsive to executable instructions in the edge luminance enhancement module that determine a sample associated with the edge-enhanced value is located at a distance from a reference point,

wherein the reference point substantially coincides with an edge of a display device.

12. A controller comprising:

an inverter configured to invert values of a pixel characteristic to establish inverted values of the pixel characteristic, the values of the pixel characteristic being predicted values of the pixel characteristic that constitute a model of backlight for a number of first samples;

an upsampler configured to upsample the inverted values of the pixel characteristic to determine upsampled values of the pixel characteristic; and

a pixel scaler configured to scale pixel data for a number of second samples by the upsampled values of the pixel characteristic to control a modulator to generate an image,

wherein the number of second samples is greater than the number of first samples.

13. The controller of claim 12 further comprising:

an edge luminance enhancer configured to scale a value of the pixel characteristic as a function of a distance from a light source to a reference point comprising an edge of a display device.

14. The controller of claim 13, wherein:

the edge luminance enhancer comprises,

a sample locator configured to determine a profiled value of the pixel characteristic as a function of the distance, and

a sample scaler configured to divide the value of the pixel characteristic by the profiled value to form a modified predicted value of the pixel characteristic.

15. The controller of claim 12 wherein the upsampler is configured to:

perform bilateral interpolation on the inverted values of the pixel characteristic to form interpolated values of the pixel characteristic.